HELP! FHA refinance how long until can purchase another FHA home?

Hey I currently live in a home (in california) that I was thinking about doing a Cash out Refinance on. And use that as downpayment on a Duplex. I want to MOVE INTO the duplex and rent out the original house plus one of the duplex units. If I do a FHA cash-out refi (on the original property) - is it true that i have to wait 12 months before i can purchase / move into a new property with a new FHA loan? I realize i have to make the original property a rental (non-owner occupied property). Wells Fargo said that I can send in a letter to the underwriter saying that my living situations have changed and they had customers that have done it within a couple months. But i talk to other banks and they said at least 10 -12 months. Does anyone have any specific information? I don't want to get stuck trying to purchase a duplex with a massive down payment.

Thanks you guys